1. Field of the Invention
The present invention relates to a digital VTR.
2. Description of the Prior Art
An analog VTR (Video Tape Recorder) for recording an image picked up by a monitoring camera on a video tape intermittently (in a time-lapse manner) at a rate of one field per predetermined several fields has already been developed.
In this type of analog VTR, when the image has been recorded to the end-of-tape of the video tape, a rewinding operation (RWD) is automatically performed. When the video tape is rewound to its beginning-of-tape, a recording operation is automatically started again.
In the above-mentioned conventional analog VTR, the image picked up by the monitoring camera is not recorded on the video tape during the rewinding operation.
An object of the present invention is to provide a digital VTR capable of recording an image picked up by a monitoring camera on a video tape while the video tape is being rewound.
A first digital VTR according to the present invention is characterized by comprising image data storage means for intermittently writing an image picked up by a video camera into a memory, image data recording means for reading out, every time image data corresponding to a predetermined recording unit are stored in the memory, the image data corresponding to the recording unit from the memory, and recording the image data on a video tape, detection means for detecting that the remaining amount of the video tape is not more than a predetermined amount, and means for automatically rewinding the video tape to its beginning-of-tape when it is detected that the remaining amount of the video tape is not more than the predetermined amount. The image data written into the memory while the video tape is being rewound can be recorded on the video tape after the rewinding.
A second digital VTR according to the present invention is characterized by comprising image data storage means for intermittently writing an image picked up by a video camera into a memory, image data recording means for reading out, every time image data corresponding to a predetermined recording unit are stored in the memory, the image data corresponding to the recording unit from the memory, and recording the image data on a video tape, detection means for detecting that the remaining amount of the video tape is not more than a predetermined amount, and means for reading out, when it is detected that the remaining amount of the video tape is not more than the predetermined amount, all the image data, which have not been recorded yet, stored in the memory, recording the image data on the video tape, and then rewinding the video tape to its beginning-of-tape. The image data written into the memory while the video tape is being rewound can be recorded on the video tape after the rewinding.
An example of the detection means is one for detecting that the remaining amount of the video tape is not more than the predetermined amount on the basis of the ratio of the number of revolutions of a feed reel to the number of revolutions of a take-up reel.
An example of the detection means is one for measuring the remaining amount of the video tape by feeding the video tape to its end-of-tape and rewinding the video tape to its original position when the image data is not recorded on the video tape, and detecting that the remaining amount of the video tape is not more than the predetermined amount on the basis of the results of the measurement.
The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.